Cabmkr's MX250B Project

[Cabmkr]

Here is what I am starting with.







Looks like most of the important bits are there and it had new piston and rings in the 80's is what I was told. a retired fella has it so it sounds like he may be the first or 2nd owner. Her had it listed as a 74 but serial number is 509-00500. Bike is about 6.5 hours from me but me mum is picking it up which gets it about an hour and a half closer.

[Iain Cameron]

Its a MX250 B 1975 not a 76 yzc . still a good bike though . Iain

[Cabmkr]

That would technically be better as I wanted a bike for pre 75 but I figured I could get away with it here in Canada as they just want to get more guys out. This is only the 2nd early monoshock I have seen in a few years on Kijiji.   

I was told the serial number is "  the serial no on engine and frame is 509 000500  " and by the angle of the motor and the curve of the clutch cover made me believe it was a YZC, but now that I look at pics of the MXB it matches it and would make more sense.... I would think that makes it a bit easier for parts. And I guess no alloy tank     The Serial number listing I was looking at was just for YZ's and the YZC starts with 509-100101

Thanks for the info! 

[Iain Cameron]

Apart from the travel and Air forks , swing arm , they were just about the same . the mx did have a alloy tank though . I might be a little of but I think the gearing and porting were slightly different too . Your right with the 509 000101 was the first mxb250 and when Yamaha has a almost no change model they re start with xxx 100101 for the next model . same with the 400 mx to the 76 yz  and the 74 125 a to 75 125yz b . Iain . Give me a pm I have a few spare bits . Ps the alloy gear shift lever is worth its wait in  gold, pure unnotainium .

[Cabmkr]

    I seen the shift lever, I figured it and the tank if its alloy should cover the cost of the bike. Would you know the difference in the travel between a YZA and the MXB?